亚洲国产日韩欧美一区二区三区,精品亚洲国产成人av在线,国产99视频精品免视看7,99国产精品久久久久久久成人热,欧美日韩亚洲国产综合乱

The following is a simple dynamic effect written in react, but the details are unclear. Why do we need to add bind(this) at the end of the timer? What is its function? What knowledge point do I lack that makes me unclear about adding bind(this)?

var Hello = React.createClass({
  getInitialState: function () {
    return {
      opacity: 1.0
    };
  },

  componentDidMount: function () {
    this.timer = setInterval(function () {
      var opacity = this.state.opacity;
      opacity -= .05;
      if (opacity < 0.1) {
        opacity = 1.0;
      }
      this.setState({
        opacity: opacity
      });
    }.bind(this), 100);
  },

  render: function () {
    return (
      <p style={{opacity: this.state.opacity}}>
        Hello {this.props.name}
      </p>
    );
  }
});

ReactDOM.render(
  <Hello name="world"/>,
  document.body
);